Multi-Wavelength PPG Glucose Sensing for Higher Non-Invasive Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-invasive blood glucose meters suffer from measurement errors due to individual differences and environmental factors, leading to reduced accuracy, especially at extreme glucose levels, and require frequent calibration.
Innovation Solution
An apparatus using two or more light sources with different wavelength bands to emit light on the body, capturing photoplethysmography signals, and deriving amplitude ratios from these signals to estimate blood glucose levels, accounting for variability in blood volume and glucose absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-invasive optical measurement is used, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent segments the measurement process by using multiple light sources with different wavelength bands (first light source for first wavelength band, second light source for second wavelength band) to separately measure hemoglobin and glucose, then combines the measurements through amplitude ratio calculation to achieve accurate blood glucose estimation without invasive procedures
Solution Approach 2:
The patent changes the parameter of light wavelength by selecting specific wavelength bands where hemoglobin and glucose have different absorption characteristics. The first wavelength band is selected where hemoglobin has high absorption, and the second wavelength band is selected where glucose has higher relative absorption, enabling differential measurement and accurate glucose calculation
2Device complexity
If single wavelength measurement is used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The measurement is segmented into two distinct wavelength band measurements, each targeting different substances (hemoglobin and glucose), with the processor separating the analysis by identifying amplitude values at specific fiducial points for each wavelength band before combining them through ratio calculation
Solution Approach 2:
The measurement system achieves multi-functionality by using the same basic PPG measurement apparatus to simultaneously obtain information about both hemoglobin (via first wavelength band) and glucose (via second wavelength band), making the device capable of measuring multiple parameters without requiring separate specialized equipment
3Ease of operation
If non-invasive measurement is used, then ease of operation is improved, but reliability deteriorates
Solution Approach 1:
The patent incorporates feedback by using the first PPG signal (measuring hemoglobin) as a reference to normalize and correct the second PPG signal (measuring glucose). The amplitude ratio calculation uses both signals to compensate for variations in blood volume, tissue thickness, and other individual differences, thereby improving measurement reliability
Solution Approach 2:
The system changes parameters by selecting wavelength bands with optimal absorption characteristics for the target substances and using amplitude ratio calculation instead of absolute amplitude measurement, making the measurement more robust against environmental factors and individual variations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves measurement accuracy by utilizing amplitude ratios from multiple wavelength bands, enhancing sensitivity to glucose and hemoglobin levels, and providing stable, precise blood glucose level estimation.
Implementation Method 1
The sensor is configured to, in response to receiving the first light and the second light having been reflected by or passed through the part of the body, respectively output a first photoplethysmography (PPG) signal and a second PPG signal
Implementation Method 2
The sensor is configured to, in response to receiving the first light and the second light having been reflected by or passed through the part of the body, respectively output a first photoplethysmography (PPG) signal and a second PPG signal
Implementation Method 3
Glucose has lower absorption level in the first wavelength band than the second wavelength band. Hemoglobin has higher absorption level in the first wavelength band than in the second wavelength band
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus and a method for non-invasive measurement of blood glucose level are provided, which are capable of driving two or more light sources to emit lights in different wavelength bands toward a part of a body of a user (e.g., a subject), deriving amplitude values from fiducial points in at least one pulse of a respective PPG signal corresponding to each wavelength band, and estimating the blood glucose level of the user using a plurality of amplitude ratios derived from the amplitude values corresponding to different combinations of wavelength bands. The lights emitted by the two or more light sources are in different wavelength bands, indicating that the lights have different characteristics of absorption coefficients for at least glucose and hemoglobin. This helps build the regression model using more data points collected for cross-referencing and calibration compared to using one light source, thereby improving overall accuracy in the estimation of the blood glucose level of the subject.